A conservative executive known on Wall Street as “I, Robot,” from his days as CEO of the New York Stock Exchange, Thain pushed to strike a deal with the encouragement of Federal Reserve officials rather than see his storied investment franchise placed in a shaky market’s cross hairs.

He took over Merrill Lynch in December from Stanley O’Neal, who had racked up tens of billions in losses on funky mortgage-related debt. A former Goldman honcho, Thain came with an impressive pedigree, and many assumed he would try to gussy up Merrill for an eventual sale.

Unlike Lehman Brothers CEO Richard Fuld, however, Thain opted to take a big balance-sheet hit now rather than wait for the market to recover. That resulted in Merrill’s shopping $30.6 billion in mortgage securities at pennies on the dollar to private-equity investor Lone Star and its stake in media company Bloomberg LP.

But after back-to-back weekends featuring the Federal Reserve bailout of Fannie Mae and Freddie Mac and the certain liquidation of Lehman, finding a bigger partner became unavoidable.

It’s too early to determine Thain’s next move, but he’s believed to have political aspirations.